JPH05232824A - Image recorder - Google Patents

Abstract

PURPOSE:To prevent soiling of a guide roller and decrease in transfer efficiency, in an image recorder which forms an electrostatic latent image on an image carrier such as a photosensitive drum, develops, transfers a toner image on a sheet and separates the sheet. CONSTITUTION:The image recorder which forms an electrostatic latent image on the image carrier 31 by means of latent image forming parts 32 and 33, develops the electrostatic latent image into a toner image by means of a developing unit 34, transfers the toner image on the image carrier 31 to a sheet PP by means of a transfer electrifier 36 and separates the sheet PP from the image carrier 31 by means of a separation electrifier 37 is further provided with the guide roller 42 which is held near a partition plate 44, separating the transfer electrifier 36 and separation electrifier 37 integrally composed on a chassis 41, with a constant gap left from the image carrier 31 and which is used fir carrying the sheet PP.

Description

Detailed Description of the Invention

(Table of Contents) Industrial Application Field of the Prior Art (FIG. 6) Problem to be Solved by the Invention Means for Solving the Problem (FIG. 1) Action Example (a) Description of One Example (FIG. 2) To FIG. 5) (b) Description of another embodiment Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for forming an electrostatic latent image on an image bearing member such as a photosensitive drum, developing it, transferring a toner image to a sheet, and separating the sheet.

In image recording apparatuses such as copiers, printers, and facsimile machines, latent image forming type recording apparatuses such as electrophotographic apparatuses are used in order to record plain paper. In such an image recording apparatus, since the electrostatic latent image is formed, developed, and the toner image is transferred to the sheet, it is necessary to smoothly convey the sheet at the transfer position.

[0004]

2. Description of the Related Art FIG. 6 is an explanatory diagram of a conventional technique. For example, in an electrophotographic apparatus, as shown in FIG. 6A, a photosensitive drum 31 is charged by a charger 32, a light image is exposed to form an electrostatic latent image according to the image, and a developing device 34 is used. The toner is developed with the toner image, the toner image is transferred to the sheet conveyed by the abutting roller 35 by the transfer charging device 36, the sheet is separated from the photosensitive drum 31 by the separation charging device 37, and the sheet is conveyed to the fixing device by the conveying roller 40. ..

In such an electrophotographic apparatus, in order to facilitate the transportation of the paper at the transfer portion, the guide roller 42 is arranged in the transport path immediately before the transfer charger 36.

[0006] To simply improve the slippage of the paper, the guide roller 42 does not transmit the driving force to the guide roller 42 and passively rotates due to the frictional force with the paper, and the paper is positively conveyed. For some purposes, the driving force is transmitted.

In order to reliably convey the paper, it is necessary to drive the guide roller 42 and to provide the position as close to the transfer charger 36 as possible. It is difficult to design the distance from the contact roller (standby) roller 35 to the transport roller 40 located downstream of the transfer charger 36 to be shorter than that of a small sheet such as a postcard. Providing the guide roller 42 immediately in front of the transfer charger 36 is an effective solution.

[0008]

However, the prior art has the following problems. Since the guide roller 42 is provided at the tip of the transfer charger 36, it is charged by the discharge corona of the transfer charger 36, adsorbs scattered matter from the developing device 34, and stains the back surface of the paper.

Particularly, in the double-sided printing apparatus, after printing on the front side, the paper is reversed and returned to perform printing, so that both printing surfaces are dirty and serious, and the user is obliged to regularly clean and replace the guide roller 42. However, there is a limit, and it requires the intervention of maintenance personnel.

When the tip of the transfer charger 36 is bent as shown in FIG. 6B, the transfer efficiency is improved. However, when the guide roller 42 is provided, the bent portion 41a cannot be provided and the transfer efficiency is improved. Is reduced.

Since the guide roller 42 is provided at the tip of the transfer charger 36, the distance between the guide roller 42 and the fixing device becomes long for printing a postcard or the like, and the conveying roller 4 is provided.
0 is required separately.

Therefore, according to the present invention, dirt on the guide roller,
An object of the present invention is to provide an image recording apparatus capable of preventing a decrease in transfer efficiency. It is another object of the present invention to provide an image recording apparatus which can easily apply a driving force while preventing the guide roller from being soiled and the transfer efficiency from being lowered.

[0013]

FIG. 1 shows the principle of the present invention. According to claim 1 of the present invention, an electrostatic latent image is formed on the image carrier 31 by the latent image forming portions 32 and 33, and the electrostatic latent image is developed into a toner image by the developing device 34, and the image carrier 31 is formed. In the image recording apparatus in which the toner image of 1 is transferred to the sheet PP by the transfer charger 36, and the sheet PP is separated from the image carrier 31 by the separation charger 37, the transfer charger 36 integrated with the chassis 41 is used. Partition plate 4 with separation charger 37
A guide roller 42, which is held near the image carrier 31 at a constant interval and which conveys the sheet PP, is provided near the position 4.

According to claim 2 of the present invention, in claim 1,
A gap roller 45 is provided at both ends of the guide roller 42 for holding the image carrier 31 at a constant interval.

A third aspect of the present invention is based on the second aspect.
The guide roller 42 and the gap roller 45 have the same axis. According to a fourth aspect of the present invention, in the third aspect, the gap roller 45 and the guide roller 42 are integrally formed, and the driving force of the image carrier 31 is applied to the guide roller 42 via the gap roller 45.
It is characterized by transmitting to and driving.

A fifth aspect of the present invention is characterized in that, in the first, second, third, or fourth aspect, the guide roller 42 is provided on the chassis 41 side, and the chassis 41 is detachable from the main body. ..

According to a sixth aspect of the present invention, in the fifth aspect,
An elastic body 11 for pressing the chassis 41 against the image carrier 31 is provided. Claim 7 of the present invention
In the sixth aspect, the elastic body 11 is made of a conductor and the chassis 41 is grounded.

According to an eighth aspect of the present invention, in the first, second, third, fourth, fifth, sixth or seventh aspect, the chassis 41 is provided on the upstream side of the sheet conveying path of the chassis 41.
A bent portion 4 in which the transfer charger 36 is bent inside
1a is provided.

According to a ninth aspect of the present invention, in the first, second, third, fourth, fifth, sixth, seventh or eighth aspect, the heat roller fixing device 39 provided downstream of the transfer charging device 36 in the sheet conveying path. Therefore, it is also characterized in that it is also used as a conveyance roller.

A tenth aspect of the present invention is as defined in claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9,
The sheet P is connected at the exit of the sheet conveying path 30 and
Backside printing conveyance path 59 for guiding P to the entrance of the conveyance path 30
Then, the sheet PP from the sheet conveying path 30 is fed in one direction, and the rear end of the sheet PP is conveyed to the back side printing conveying path 5.
9, sheet reversing mechanisms 54 and 55 for conveying the sheet to the rear surface printing conveying path 59 are provided.

[0021]

According to the first aspect of the present invention, the sheet is held near the partition plate 44 of the transfer charger 36 and the separation charger 37, which are formed integrally with the chassis 41, at a constant interval from the image carrier 31. Since the guide roller 42 for conveying the PP is provided, firstly, the guide roller 42 is used as the transfer charger 3.
6 is charged, but since the charge is removed by the separation charger 37,
Adsorption of scattered matter can be greatly reduced, there is no risk of soiling the sheet PP, and secondly the tip of the chassis 41 is opened, so that a bent portion can be formed at the tip of the chassis 41, and transfer efficiency is improved. Since the distance to the fixing device can be shortened, it is not necessary to separately provide a conveyance roller.

In the second aspect of the present invention, the guide roller 42 is used.
Since the gap rollers 45 for holding the image carrier 31 at a constant interval are provided at both ends of the above, the interval can be easily maintained.

In the third aspect of the present invention, the guide roller 42 is used.
Since the axial centers of the gap rollers 45 are the same, the intervals can be kept constant with a simple structure. Claim 4 of the present invention
Then, since the gap roller 45 and the guide roller 42 are integrally formed, and the driving force of the image carrier 31 is transmitted to the guide roller 42 via the gap roller 45, the guide roller 42 is driven. It can be driven by the driving force of the image carrier 31 and can be easily realized.

In the fifth aspect of the present invention, the guide roller 42
Is provided on the chassis 41 side, and the chassis 41
Since it can be detached from the main body, the guide roller 42 can be replaced together with the transfer charger 36 and the like.

According to the sixth aspect of the present invention, since the elastic body 11 for pressing the chassis 41 against the image carrier 31 is provided, the guide roller 42 can be driven by the driving force of the image carrier 31 with a simple structure.

According to the seventh aspect of the present invention, since the elastic body 11 is made of a conductor and the chassis 41 is grounded, the grounding can be easily and easily performed. According to claim 8 of the present invention, on the upstream side of the sheet conveyance path of the chassis 41,
Since the chassis 41 is provided with the bent portion 41a that is bent inside the transfer charger 36, the transfer charger 36
The transfer efficiency of the sheet can be improved, and the sheet can be conveyed by the guide roller 42.

According to a ninth aspect of the present invention, a heat roller fixing device 39 provided downstream of the transfer charging device 36 in the sheet conveying path.
Thus, since the conveyance roller is also used, the conveyance roller can be reduced even when handling a short sheet such as a postcard.

In the tenth aspect of the present invention, the rear surface printing conveyance path 59 that connects the sheet conveyance path 30 at the exit and guides the sheet PP to the entrance of the conveyance path 30, and the sheet PP from the sheet conveyance path 30. The sheet P in one direction
Since the rear end of P is directed to the back side printing conveyance path 59 and the sheet reversing mechanisms 54 and 55 for conveying to the back side printing conveyance path 59 are provided, even when double-sided printing is performed, the guide roller 42 causes
It is possible to prevent stains on both printing surfaces and improve transfer efficiency.

[0029]

【Example】

(a) Description of an Embodiment FIG. 2 is a block diagram of an image recording apparatus according to an embodiment of the present invention.
2 shows an electrophotographic printer capable of double-sided printing.

In FIG. 2, the image recording apparatus 1 comprises a paper cassette 2, a printing mechanism 3 and a conveying system 5. The printing mechanism 3 comprises an electrophotographic unit and is capable of double-sided printing. Has been done.

The printing mechanism 3 includes a conveying path 30, a rotating photosensitive drum 31, and a charger 32 that charges the photosensitive drum 31.
An optical system unit 33 for writing an optical image on the photosensitive drum 31 to form a latent image, a developing device 34 for developing the latent image on the photosensitive drum 31 with toner, and a standby roller for waiting a sheet to be transferred. 35, a transfer charger 36 that transfers the toner image on the photosensitive drum 31 to the sheet sent by the standby roller 35, a separation charger 37 that separates the sheet PP from the photosensitive drum 31, and the photosensitive drum 31 after transfer. And a heat roller fixing device 39 that heat-fixes the toner image on the paper.

The sheet conveying system 5 includes a pick roller 50 for picking a sheet in the sheet cassette 2 and conveying rollers 51, 52, 53 for conveying a big sheet to the standby roller 35.
And an impeller 54 for directing the trailing edge of the paper from the heat roller fixing device 39 to the back side printing conveyance path 59, and the heat roller fixing device 39
After the sheet from the sheet is conveyed in the discharge direction, the switchback roller 55 is sent to the conveyance path 59 for back side printing, the guide roller 56 for guiding the sheet discharge, and the discharge roller 57.
And a discharge tray 58 for storing the discharged paper, and a backside printing conveyance path 59 for feeding the paper from the switchback roller 55 to the standby roller 35 by the conveyance rollers 59a and 59b for backside printing.

The operation of the image recording apparatus 1 is that the paper cassette 2 is picked by the pick roller 50,
1, 52, 53 are fed to the standby roller 35, and the charger 32
Is charged with, an optical image is written by the optical system unit 33,
A latent image is formed and synchronized with the toner image on the photosensitive drum 31 on which the toner image is formed by the developing device 34.

The toner image of the photosensitive drum 31 is transferred onto the surface of the paper sent by the standby roller 35 by the transfer charger 36, separated from the photosensitive drum 31 by the separation charger 37, and fixed by the heat roller fixing device 39. Is sent to the switchback roller 55, and the switchback roller 55
It is conveyed in the direction of the discharge tray 58.

When the trailing edge of the paper reaches the impeller 54,
When the switchback roller 55 stops the conveyance operation and stops the sheet, the rear end of the sheet rotates in the counterclockwise direction of the impeller 54, so that the rear end of the sheet faces the conveyance path 59 for back side printing, and the switchback is performed. The roller 55 sends the paper to the back side printing conveyance path 59, and the paper is sent to the standby roller 35 by the conveyance rollers 59a and 59b of the back side printing conveyance path 59.

Thereafter, as in the case of front surface printing, the standby roller 35
The toner image of the photosensitive drum 31 is transferred to the back surface of the paper by the transfer charger 36, separated from the photosensitive drum 31 by the separation charger 37, fixed by the heat roller fixing device 39, and switched by the switchback roller 55. Is sent to the discharge tray 58 by the switchback roller 55,
The paper is discharged onto the discharge tray 58 by the discharge roller 57, and double-sided printing is performed.

In the case of single-sided printing, only the front side is printed and the sheet is discharged to the discharge tray 58. Such a printing apparatus 1 is
Since the sheet cassette 2 is mounted from the front side, accommodated in the apparatus, and discharged to the upper discharge tray 58, space is not required on both sides, space can be saved, and the discharge path is used as a switchback. Therefore, the device can be downsized and double-sided printing can be performed.

FIG. 3 is a schematic view of an embodiment of the present invention, FIG. 4 is an enlarged view of a main part of the embodiment of the present invention, and FIG. 5 is a schematic view of a main part of the embodiment of the present invention. As shown in FIGS. 3 and 4, the transfer charger 36 having the transfer wire 36a and the separation charger 37 having the separation wire 37a are integrated by a chassis 41 and are separated by a partition plate 44.

The chassis 41 is detachably attached to the block 10 of the apparatus main body. The chassis 41 on the upstream side of the transfer charger 36 forms a bent portion 41a that is bent inward, and the tip thereof is the photosensitive drum 3
It is arranged so that it is spaced from 0.3 to 0.5 mm with respect to 1,
In order to prevent the leak from the corona wire 36a, the bent portion 41a is covered with an insulating tape on the inner side, and the chassis 41 and the partition plate 44 are made of a stainless plate material.

The guide roller 42 has its axis centered right above the partition plate 44 and has a diameter of 6 mm. 43
Is a gap roller for maintaining a distance between the chassis 41 and the photosensitive drum 31.

As shown in FIG. 5 (A), the guide roller 42 has a roller shape of a uniform cylindrical shape in the longitudinal direction,
A shaft 42a having a diameter of 2 mm was erected in the longitudinal direction at the center of the rollers at both ends, and an insulating resin was used as the material.

The gap rollers 45 are arranged at both ends of the guide roller 42, and a hole having a diameter of 2 mm is formed in the center thereof, and the shafts 42a at both ends of the guide roller 42 are passed through the holes to connect the guide roller 42 and the gap roller 45. It was fixed with an adhesive.

As shown in FIG. 5B, the guide roller 42 is provided with resin housings 46 for fixing wires on both ends of the chassis 41, and an upper portion of the housing 46 is provided with
A bearing integrated with the housing 46 was arranged with resin, and the shaft 42a of the guide roller 42 was inserted into the bearing and fixed rotatably.

As shown in FIG. 3, a standby roller 35 and a heat fixing roller 39 are arranged on the sheet conveying path 30 before and after the transfer charger 36, and the standby roller 35 and the guide roller 4 are provided.
The path length up to 2 and the path length from the guide roller 42 to the heat fixing roller 39 are set within 140 mm.

To ground the chassis 41 to the ground, as shown in FIG. 5 (B), a bent stainless plate material (thickness 1 mm) is placed under the chassis 41 of the block 10, and the chassis 41 The transfer charging device 36 was pressed against the photosensitive drum 31 due to the elasticity of the stainless steel plate by bringing it into contact with the back surface and conducting it.

With this structure, the guide roller 42
Is provided right above the partition plate 44 of the chassis 41, the guide roller 42 is charged by the transfer charging device 36, but is discharged by the separation charging device 37, so that scattered particles such as toner are less attracted. Therefore, the sheet PP can be conveyed while preventing the sheet PP from being soiled.

Since the tip of the chassis 41 can be opened,
The bent portion 41a can be formed at the tip of the chassis, the transfer efficiency of the transfer charger 36 can be prevented from being lowered, and the conveyance of the sheet PP and the toner transfer can be further improved.

Since the guide roller 42 is close to the heat fixing roller 39, even for short paper such as a postcard, the heat fixing roller 39 can also serve as a carrying roller without the need to separately provide a carrying roller.

Since the guide roller 42 is provided on the chassis 41, the chassis 41 is replaced and
The guide roller 42 can be replaced, and the maintainability with respect to the dirt of the guide roller 42 is improved.

Since the guide rollers 42 are provided with the gap rollers 45 at both ends, they can be maintained at a constant distance without contacting the photosensitive drum 31, and the gap rollers 45 are provided on the shaft 42a. Since the gap can be maintained and the gap roller 45 is fixed to the guide roller 42, the rotational force of the photosensitive drum 31 can be transmitted to the guide roller 42, and the conveying force can be applied to the guide roller 42.

Further, the chassis 41 is a leaf spring 11,
Since it is pressed against the photosensitive drum 31, the photosensitive drum 31
The gap roller 45 to the photosensitive drum 3 regardless of the eccentricity of
1 can be pressed against the guide roller 42, and the guide roller 42 can be held at a constant interval by the rotation force of the photosensitive drum 31.
Can be rotated.

Since the leaf spring 11 is electrically conductive, the chassis 41 can be grounded. In this way, when applied to an image recording apparatus for double-sided printing, the guide roller 42 does not stain both printing surfaces of the paper PP, so the guide roller 42
Even if it is provided, clean double-sided printing is possible.

(B) Description of Other Embodiments In addition to the above embodiments, the present invention can be modified as follows. In the above-described embodiment, the printing mechanism 3 is described as an electrophotographic mechanism, but the printing mechanism 3 can also be used as a printing mechanism that transfers a toner image (for example, an electrostatic recording mechanism or the like).

The sheet PP is not limited to paper, and other media can be used. Although the image recording device is described as a printer, it may be another image recording device such as a copying machine or a facsimile.

The present invention has been described above with reference to the embodiments.
Various modifications are possible within the scope of the invention, and these modifications are not excluded from the scope of the invention.

[0056]

As described above, according to the present invention,
It has the following effects. Near the partition plate 44 of the transfer charger 36 and the separation charger 37, the sheet PP is held at a constant interval with the image carrier 31.
Since the guide roller 42 for transporting the toner is provided, the guide roller 42 is charged by the transfer charger 36, but is discharged by the separation charger 37, so that it is possible to greatly reduce the adsorption of scattered materials such as toner, and seek. There is no risk of polluting PP.

Since the tip of the chassis 41 is opened,
A bent portion can be formed at the tip of the chassis 41, and transfer efficiency can be improved. Since the distance to the fixing device can be shortened, it is not necessary to separately provide a conveyance roller.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of an image recording apparatus according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of an embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of one embodiment of the present invention.

FIG. 5 is a configuration diagram of a main part of an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 1 Image Recording Device 2 Paper Cassette 3 Printing Mechanism 5 Transport Mechanism 10 Block 11 Leaf Spring 30 Paper Transport Path 31 Photosensitive Drum (Image Carrier) 32 Charger 33 Optical Unit 34 Developer 35 Standby Roller 36 Transfer Charger 37 Separation Charger 39 Heat roller fixing device 41 Chassis 41a Bending part 42 Guide roller 44 Partition plate 45 Gap roller 46 Housing

Claims (10)

[Claims] 1. A latent image forming portion (32,
33) forms an electrostatic latent image, the developing device (34) develops the electrostatic latent image into a toner image, and the toner image on the image carrier (31) is transferred to a sheet (PP) by a transfer charger (36). ), And the separation charger (37) separates the sheet (PP) from the image carrier (31), the transfer charger (3) integrated with the chassis (41).
A guide roller (42) for conveying the sheet (PP), which is held at a constant distance from the image carrier (31), is provided in the vicinity of a partition plate (44) between the image carrier (31) and the separation charger (37). An image recording device characterized by the above. 2. The image recording apparatus according to claim 1, wherein gap rollers (45) for holding the image carrier (31) at a constant interval are provided at both ends of the guide roller (42). .. 3. The image recording apparatus according to claim 2, wherein the guide roller (42) and the gap roller (45) have the same axis. 4. The gap roller (45) and the guide roller (42) are integrally formed, and the driving force of the image carrier (31) is applied to the guide roller (42) via the gap roller (45). 4.) The image recording apparatus according to claim 3, wherein the image recording apparatus drives the image recording apparatus. 5. The guide roller (42) is provided on the chassis (41) side, and the chassis (41) is detachable from the main body.
Alternatively, the image recording device of 3 or 4. 6. The image recording apparatus according to claim 5, further comprising an elastic body (11) for pressing the chassis (41) against the image carrier (31). 7. The elastic body (11) is made of a conductor,
The image recording apparatus according to claim 6, wherein the chassis (41) is grounded. 8. A bending portion (41a), which is formed by bending the chassis (41) inside the transfer charger (36), is provided on the upstream side of the sheet conveying path of the chassis (41). The image recording device according to claim 1, 2 or 3 or 4 or 5 or 6 or 7. 9. A heat roller fixing device (39) provided downstream of the sheet conveying path of the transfer charger (36),
9. The image recording apparatus according to claim 1, wherein the image forming apparatus is also used as a conveying roller. 10. A back side printing conveyance path (59), which is connected at the exit of the sheet conveyance path (30) and guides the sheet (PP) to the entrance of the conveyance path (30), and the sheet conveyance path (30). ), A sheet reversing mechanism that feeds the sheet (PP) from one side in one direction and directs the rear end of the sheet (PP) to the back side printing conveyance path (59) and conveys it to the back side printing conveyance path (59). (54, 55) is provided, 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9
Image recording device.